The invention relates to a process for the treatment of waste paper, sometimes referred to herein as with the exclusion of biocides and the total exclusion of chlorine compounds as well as with the virtual avoidance of hydrogen peroxide and/or peracetic acid, which also yields a recycled base tissue and optionally, to a tissue product that is suited for final consumption and that has a total germ count of less than 1000 CFU/g (colony-forming units per gram); the invention also relates to a device to carry out this process as well as to recycled base tissue paper and optionally, a tissue product that is suited for final consumption and that has a surface germ count of less than 20 CFU/dm2 and a total germ count of less than 1000 CFU/g as a product. The above-mentioned germ counts are determined in a manner similar to DIN 54378 (surface germ count) and in a manner similar to DIN 54379 (total germ count).
The expression xe2x80x9cwith the exclusion of biocides,xe2x80x9d which is used in conjunction with the process according to the invention, refers to biocide quantities that are present in small quantities, preferably in quantities of less than 0.01% by weight relative to the recycled base tissue or to the tissue product that is suited for final consumption.
Moreover, in this context, it should also be pointed out that the clear water that is used within the scope of the process according to the invention (for example, as a temperature-control medium in the papermaking machine, as shown in FIG. 1) is circulated and purified by means of a circulating-water treatment system (Sedifloat); right from the start, this water only has concentrations of biocide substances that lie below the detection limit of less than 0.1 ppm, since its HPLC analysis was negative. The DCM extract that was examined did not reveal any biocide either. As is known, in the above-mentioned circulating-water treatment system, the fine substances and fillers are separated almost quantitatively from the water and thus the treated water is used again for dilution purposes.
The article in the PTS Manuscript Volume 19/95, titled Microbiocides in Papermaking, Hygienic Aspects of the Use of Various Grades of Old Paper, by U. H{umlaut over (oo)}tmann, gives a general overview as to which starting materials, for example, a fiber raw material recovered from mixed household garbage, from mixed old paper, from industrial waste or mixed old paper or from raw material obtained from collections within the scope of Germany""s Dual System can be used for waste paper processes. This general overview, however, does not provide any information that could anticipate the process according to the invention as claimed.
German Patent No. 26 07 703 relates to a process for the production of sanitized recycled paper made of waste containing paper, whereby a fractionxe2x80x94consisting essentially of paper fragments or a mixture of paper and plastic fragments which are retained by a screen having a mesh size of at least 20 mmxe2x80x94is separated from the waste in a generally known manner and is then subjected to a brief thermal treatment, whereby the fragments are heated to a temperature ranging from about 100xc2x0 C. to 130xc2x0 C. [212xc2x0 F. to 266xc2x0 F.], whereupon the fragments, optionally after separation of the plastic fraction, are compacted while a temperature of at least 100xc2x0 C. [212xc2x0 F.] is maintained, and the compacted fragments are kept at a temperature of about 100xc2x0 C. to 110xc2x0 C. [212xc2x0 F. to 230xc2x0 F.] for at least 24 hours at the appertaining temperature limit. The heat treatment is carried out by means of IR heat, that is to say, dry heat. This process is based on the objective of producing recycled paper that, in contrast to conventional processes, is no longer laden with a bacteria content in the order of magnitude of 109 heterotrophic colony-forming bacteria per gram of product and with an unknown amount of mold and mildew as well as with thermophilic organisms that not only pose a threat to the health of the operating personnel but that also lead to annoying odor and slime problems in the return water system of the papermaking machines. According to this process, the bacteria content is reduced to about 102 bacteria per gram of weighed-in material.
However, this state of the art does not suggest the subject matter of the present invention as claimed, that is to say, working in a medium containing water or in moist heat, nor does it give any indication that, by means of this process, the spores of the bacteria or fungi are to be activated before the germination.
European Preliminary Published Application No. 0,514,864 relates to a process for the treatment of secondary pulp comprising cellulose fibers and tacky contaminants that is made of old paper, whereby the pulp is brought into contact with a gas containing oxygen without added alkali under such conditions in terms of temperature and oxygen partial pressure and for such a period of time that the stickiness of the tacky contaminants is diminished, thus reducing problems involving operating conditions and relating to the product quality during the further processing of the cellulose fibers into the recycled paper product. This contacting procedure is preferably carried out at a temperature between 60xc2x0 C. and 130xc2x0 C. [140xc2x0 F and 266xc2x0 F.] at an oxygen partial pressure ranging from 34.5 to 3,100 kPa.
The outcome of this process is, on the one hand, a product with a low percentage of old paper that already has a suitable strength for special application purposes and, on the other hand, a product with a high proportion of recycled paper that can be used, for example, for newspapers, diapers, tissues, writing paper and printing paper. This state of the art is based on the objective of providing a treatment process of the type mentioned above for secondary pulps. This state of the art, however, makes no mention of the production of a recycled paper that is produced so as to be essentially free of biocides and that, as a result of this process, has a surface germ count of less than 20 CFU/dm2.
European Patent Specification No. 0,394,734 relates to a process for the sterilization of objects, preferably packaging material, using a gaseous sterilization means. However, this publication does snot give any indication of parallels to the treatment process according to the invention which functions without the use of biocides and which leads to a low bacterial load in the product of the process.
German Patent No. 3,001,862 relates to a process for the production of raw material for paper production using old paper, whereby old paper from trash is already treated with a disinfectant gaseous means when it is sorted out from the trash and only subsequently is the old paper treated, especially by means of dissolution and defiberization, for purposes of paper production. Ozone or chlorine are preferably used as the disinfectant or biocide. This neither anticipates nor suggests the process according to the invention, since this process of the state of the artxe2x80x94in contrast to the process according to the inventionxe2x80x94is a dry process that makes use of disinfectants.
German Preliminary Published Application No. 2,214,786 relates to a process for the destruction of files and spent packaging tubes made of paper or paperboard, whereby the material to be disintegrated is first mechanically shredded and the shredded product is then compacted for purposes of volume reduction, whereby the shredded product is moistened before the compacting step. Preferably, ink-degrading as well as bactericidal substances and optionally binders are added to the water. Another subject matter of this state of the art is a suitable device to carry out the above-mentioned process. This state of the art is based on the objective of creating a process and a device of the above-mentioned type with which the shredded material can be compacted very tightly and also kept in this compacted form so that further treatment is facilitated. This does not suggest the process according to the invention whose objective is rather to provide a process for the preparation of old paper without the use of biocides so as to manufacture paper that is largely free of spore-forming microorganisms and that has a low total germ count.
U.S. Pat. No. 5,324,432 relates to a process to inhibit filamentous growing bacteria in water streams from industrial processes, whereby a protease enzyme is added to the water streams together with a biocide in such a quantity that the components interact to kill the bacteria. Process water types used in the pulp and paper mill industry are preferably used as the process water. This state of the art is based on the objective of lowering the bacterial load in industrial process water streams by adding a biocide as well as an enzyme. In particular, this makes it possible to markedly reduce the bacterium Sphaerotilus natans. However, this state of the art does not suggest the subject matter of the present invention as claimed, namely, the creation of a treatment process for old paper without the use of biocides that yields a process product with a very low germ count.
World Patent No. 92/18638 relates to a process for the hydrolysis of water-insoluble esters in the presence of a special lipase, whereby they are converted at an acidic pH value in the presence of an aluminum salt. Preferably, the above-mentioned ester hydrolysis process is used during a pulping or papermaking process. This state of the art is based on the objective of increasing the hydrolysis rate of esters in the presence of lipases by adding chemicals. This does not suggest the subject matter of the present invention as claimed, namely, the creation of a treatment process for old paper that yields a process product with a very low germ count.
German Patent No. 3,741,583 relates to a process to destroy microbes that cause precipitates, form slime and/or impair the quality of food-grade paper or paperboard, said process being used in the production water of papermaking plants, whereby a lytic enzyme with glucanase and protease activity that destroys the microbe cell walls is added to the production water in the papermaking plant. Using this process and the enzyme preparation, the growth of Aspergillus nigerxe2x80x94a mold that is commonly found in the paper industryxe2x80x94is reduced, and so is the growth of Bacillus subtilis and yeast sp.1696. This, however, neither anticipates nor suggests the process according to the invention, since this state of the art describes a completely different objective.
The publication by T. Yoda, M. Tsutoma and M. Osamu, Production of Paper Fibers from Community Waste, in the Conference Report titled xe2x80x9cRecyclingxe2x80x9d, Berlin 1979, pages 1299 to 1304, relates to a process to recover paper fibers by means of a wet process to treat the product, which is contaminated with Coli bacteria in the order of magnitude of 106 germs per gram of material; by using hypochlorites, the number of these Coli bacteria can be reduced to 103 germs per gram of material. The material obtained from the sterilization and simultaneous bleaching with hypochlorite is made of initial materials such as newspaper and magazine paper, corrugated cardboard and writing paper or white paperboard, and it can be further processed into a fibrous material that could be used for the middle and bottom layers of white paperboard and corrugated cardboard together with other fibers; conceivably, this fibrous material could also be used for writing paper and toilet paper of a lesser grade. However, this process neither anticipates nor suggests how to arrive at the process according to the invention in question.
The article in the journal Paper, dated Jun. 10, 1985, no. 10, vol. 203, pages 23 to 29, describes a processing of fibers at a number of Austrian and German companies in the paper industry. As representative examples, a description is given of recycling at the Austrian company Neupack by means of a thermal treatment of the old-paper starting material at 90xc2x0 C. [194xc2x0 F.] as well as at the German company FS Karton with a steam treatment unit at a temperature of 140xc2x0 C. [284xc2x0 F.] that kills all bacteria, although no mention is made of bacterial spores. Aside from this isolated information, the state of the art does not give any information that would suggest the process according to the invention. In particular, it is not stated that the temperature increase is used specifically to induce spore germination, as is done in the process according to the invention.
The monograph titled xe2x80x9cPossibilities for the use of fiber material from household garbage in paper and paperboard manufacturexe2x80x9d by H. Stark, Vol. 2, Berlin, Germany, pages 1145 to 1152, relates to laboratory experiments as well as to a large-scale study with old paper from trash for the production of a low-grade, coated gray paperboard with a substance of 350 g/m2. Within the scope of this process, after the material has been deckered to 30%, it is dispersed at about 95xc2x0 C. [203xc2x0 F.], as a result of which it has been shown that the germ count is reduced by more than 99%; thus, the finished paperboard only contains germs in the order of magnitude of between 160 and 85 germs per gram of paperboard. These general statements, which did not include the production of tissue paper, do not suggest the process according to the invention since in the latter process, substantially lower germ counts are obtained without using an additional biocide.
The publication titled xe2x80x9cResearch into the hygienic qualities of paper recovered by mechanical sorting of municipal wastexe2x80x9d by H. W. Kindler, published in Recycling World Congress 1, Basel, Switzerland, 1978, Paper 2/4, relates to a treatment process of the Escher Wyss company in which paper fibers from an old-paper starting material are used for recycling. The process of fiber production consists of the steps of dissolving old-paper particles in a pulper, adding fresh water and a screen press effluent, followed by a treatmentxe2x80x94for example, in an intermediate tankxe2x80x94in a cleaning device, a defiberizer, a central cleaning unit, a vibration frame and the dewatering on a double mesh net, heating the crumbly material up to 90xc2x0 C. [194xc2x0 F.], using steam at a temperature of 162xc2x0 C. [323.6xc2x0 F.] a heating spiral in order to plasticize the dirt particles and reduce the bacteria fraction, followed by a screening of the fibers in a disperser and a discharge of the material to a papermaking plant at 45xc2x0 C. [113xc2x0 F.]. However, this sequence of steps neither anticipates nor suggests the process according to the invention, in particular, no indication is given as to whether the bacteria fraction, and especially the fraction of microorganisms capable of spore formation, can be reduced to germ counts of less than 100 colony-forming units per gram of product.
An article by J. M. Clxc3xa9ment in the 1993 yearbook of the Papermakers Conference describes the new JMC process, which makes use of a decontamination procedure to remove contaminants such as glues and hot melts. However, this article does not state that no biocides are used during the treatment of the old paper or that, at the same time, a product with only a low germ count is obtained.
The article by G. W. Gove and J. J. McKeown in Tappi, the issue of November 1975, Vol. 58, page 121 gives an overview of disposal practices in old-paper processing. However, this general article does not indicate what approach would be taken within the scope of processing old paper in order to obtain a process product that is largely free of sporeforming microorganisms without the use of biocides.
The article by S. J. Poock in Tappi Journal, August 1985, page 78 ff. relates to microbial contamination when starch is used during paper manufacture. In this context, special mention should be made of the fact that biocides should be used in this case. Thus, this state of the art neither anticipates nor suggests not using any biocides while nevertheless obtaining a process product that is extremely low in germs within the scope of a process for the treatment of old paper.
The article by W. Salzburger et al. titled xe2x80x9cThe Cell""link concept for optimizing the use of chemicals in the deinking processxe2x80x9d, published in the Weekly for Paper Manufacture, Vol. 13, 1996, page 592 ff., describes a new process that achieves an optimal utilization of the deinking chemicals peroxide, sodium hydroxide solution and water glass. This translates into a targeted savings on chemical that has an influence on the degree of whiteness and the residual peroxide content of the deinked recycled material. This, however, neither anticipates nor suggests using biocides, chlorine compounds, hydrogen peroxide and/or peracetic acid in order to obtain a largely germ-free process product within the scope of a process for the treatment of old paper.
In addition to the usual vegetative forms of life of microorganisms, the old-paper starting product contains spores (permanent forms) of sporulating microorganisms.
The present invention is based on the objective of providing a treatment of old paper without the use of biocides and chlorine compounds as well as with the virtual avoidance of hydrogen peroxide and/or peracetic acid, whereby the paper is largely free of sporeforming microorganisms. In addition to shredding and cleaning, the old-paper treatment according to the invention also encompasses a minimization of the microbial contamination of the old paper used.
Accordingly, the present invention provides a process for the treatment of waste paper containing spores of sporulating microorganisms, without the use of biocides and chlorine compounds as well as with the virtual avoidance of hydrogen peroxide and peracetic acid, including the following process steps: treating the waste paper starting material in an environment containing water in order to activate the microorganism spores, germinating the spores, further processing the material in at least one separation stage at temperatures above room temperature, hot dispersing the further processed material in a water vapor atmosphere at a pressure greater than atmospheric pressure, subjecting the dispersed material to a temperature-controlled treatment and processing into a largely spore-free recycled pulp, and from that into a largely spore free base tissue with a total germ count of less than 1000 CFU/g and a surface germ count of less than 20 CFU/dm2.
Thus, the present invention relates to a process for the treatment of old paper without the use of biocides and chlorine compounds andxe2x80x94with the virtual avoidance of hydrogen peroxide and/or peracetic acidxe2x80x94for the production of a recycled base tissue with a total germ count that is lower than 1000 CFU/g and a surface germ count of less than 20 CFU/dm2, comprising the following process steps:
the treatment of the pre-sorted and/or unsorted, optionally pre-shredded, old-paper starting material in an environment containing water in order to activate the micro-organism spores,
the induction of germination of the spores,
the germination of the spores,
the further processing of the old-paper starting material containing germinated spores, preferably in at least one sorting stage in a generally known manner at temperatures between 20xc2x0 C. and 70xc2x0 C. [68xc2x0 F. and 158xc2x0 F.], optionally comprising
pre-sorting,
flotation,
fine sorting,
washing and deckering while returning the separated and de-pulped clear water, all the way to the dissolving stage, followed by
a dispersion (hot treatment) of the paper starting material to be further processed in a water vapor atmosphere at atmospheric overpressure, a subsequent temperature-controlled treatment and
a subsequent substance dilution using papermaking machine return water and
processing in a generally known manner into a virtually spore-free recycled pulp and from this, into a virtually spore-free recycled base tissue or a tissue product that is suited for final consumption. The above-mentioned temperature-controlled treatment should generally take at least 120 minutes.
According to a preferred embodiment of the treatment process according to the invention, a thermal treatment, a treatment by means of ultrasound, a treatment by means of ultraviolet light or a suitable enzymatic or chemical treatment serves as the spore-activating treatment.
In another preferred embodiment of the process according to the invention, an old-paper starting material dispersed in water is used as the environment containing water for the old-paper starting material.
In another preferred embodiment, the residual moisture of the old-paper starting material is 5% to 15% by weight, preferably 7% to 13% by weight, and especially 9% to 10% by weight. The term residual moisture as defined by the invention is the percentage of water present in the old-paper starting material.
Moreover, commonly employed auxiliaries and additives such as up to 2% by weight of sodium hydroxide, up to 3% by weight of water glass, deinking auxiliaries such as soaps, enzymes or surfactants in amounts of up to 2% by weight as well as commonly employed complexing agents in amounts of up to 2% by weight, each relative to the air-dry starting material, can be added to this old-paper starting material that is dispersed in water. xe2x80x9cAir-dry starting materialxe2x80x9d definition: see DIN 6730 1996-05.
In another preferred embodiment, the subsequent germination of the spores takes place over a period of 60 to 120 minutes, preferably 70 to 100 minutes, at temperatures of 20xc2x0 C. to 70xc2x0 C. [68xc2x0 F. to 158xc2x0 F.], preferably 30xc2x0 C. to 60xc2x0 C. [86xc2x0 F. to 1400F]. Here the pulp consistency is 1% to 10% by weight, preferably 3% to 5% by weight.
According to another preferred embodiment of the treatment process according to the invention, the subsequent dispersion is carried out in a water vapor atmosphere above atmospheric pressure, preferably at a pressure of 0.1 to 4 bar, especially 1.2 to 1.6 bar. Here, the pulp consistency is 15% to 50% by weight, preferably 25% to 35% by weight.
According to another preferred embodiment, the dispersion is carried out at temperatures of 100xc2x0 C. to 140xc2x0 C. [212xc2x0 F. to 284xc2x0 F.], preferably at 110xc2x0 C. to 130xc2x0 C. [230xc2x0 F. to 266xc2x0 F.], especially at about 121xc2x0 C. [249.8xc2x0 F.], for a period of time that is sufficient to kill off the germinated microorganisms in the mixture.
According to another preferred embodiment of the treatment process according to the invention for old paper, subsequent to the dispersion, a thermal (temperature-controlled) treatment is carried out for a period of time of at least 120 to 240 minutes, preferably 150 to 180 minutes. Here the pulp consistency is 5% to 16% by weight, preferably 10% to 14% by weight. With this thermal treatment, the temperatures normally used are about 50xc2x0 C. to 90xc2x0 C. [122xc2x0 F. to 194xc2x0 F.], preferably 60xc2x0 C. to 85xc2x0 C. [140xc2x0 F. to 185xc2x0 F.], and especially 70xc2x0 C. to 80xc2x0 C. [158xc2x0 F. to 176xc2x0 F.].
The above-mentioned sporulating microorganisms are preferably spores of algae, fungi and/or bacteria which differ from the usual vegetative life forms of microorganisms in that they form endospores. The frequently occurring vegetative cells are normally Pseudomonas of various species; these are usually present in the old-paper starting material in an amount of 105 to 107 CFU/g. Moreover, species of bacillus are commonly found in old-paper starting materials, and they are present in bacterial counts between 103 and 104 CFU/g. The total bacterial count is, of course, higher by several powers of ten. Due to the formation of highly heat-resistant spores, these bacteria survive the passage through the dry segment of the process according to the state of the art, for example, through a tissue or papermaking machine. Furthermore, mold spores are also found in old-paper starting materials, although they only add to the microbiological load if the production takes place in a neutral or slightly acidic pH range. In addition, yeast with germ counts between 104 and 108 CFU/g are found in individual cases, and finally, there are also anaerobic micro-organisms such as sulfate reducers in some systems. Last but not least, in some cases, it is also possible for anaerobic spore-forming bacteria such as, for example, Clostridia, to grow in anaerobic zones.
According to another preferred embodiment, the old-paper starting material used has already been pre-sorted according to the individual components and selected from low-grade, medium-grade or high-grade paper as well as kraft paper as defined in European Standard EN 643.
Low-grade paper, as defined in the above-mentioned standard and as can be used according to the invention, refers to originally mixed old paper, mixed old paper and cardboard (unsorted), sorted mixed old paper and cardboard, paperboard cuttings, retail store old paper, corrugated cardboard, corrugated cardboard chips (new), illustrated magazines, illustrated brochures without glued spines, newspapers and brochures (mixed), newspapers and brochures without glued spines (mixed), brochures and magazines (mixed) as well as shredded office paper (mixed).
Medium-grade paper, as defined in the above-mentioned standard and as can be used according to the invention, refers to old newspapers, magazines, over-issues, sections of multi-layer paperboard with a white layer, chips in mixed colors, magazine chips, magazine chips (free of glued spines), colored folders, books without covers (wood-free), books, heavy stock, white carbonless paper, colored carbonless paper, bleached coated polyethylene paperboard, polyethylene-coated paperboard as well as office paper containing wood throughout.
High-grade paper, as defined in the above-mentioned standard and as can be used according to the invention, refers to pastel mixed printed chips, bright colored mixed printed chips (wood-free), printed cards (mixed colors), non-compacted printed wood-free white office paper, punch cards (chamois colored), white files (mixed), white files (wood-free), white continuous-feed forms (wood-free), white continuous-feed forms (wood-free, non-dyeing), white multi-layer paperboard with imprint, white multi-layer paperboard (not printed), white newsprint, white magazine printing paper, coated paper (white, containing wood), coated paper (white, wood-free), white chips containing wood, white chips (mixed) white chips (wood-free) as well as white chips (wood-free, not coated).
Kraft paper, as defined in the above-mentioned standard and as can be used according to the invention, refers to brown corrugated cardboard, kraft corrugated cardboard II, kraft corrugated cardboard I, kraft paper bags (used), kraft paper bags (used, clean), kraft paper (used) as well as kraft paper (new). Any mixtures of the above-mentioned components of each group can be used according to the invention.
According to another preferred embodiment, the processing of the old-paper starting material passes through the intermediate stage of a largely spore-free recycled pulp to the largely spore-free recycled base tissue in a generally known manner, and then, likewise in a generally known manner through a further process, for example, that yields the corresponding tissue paper products, preferably in the form of single-layer or multi-layer folded products and/or rolled products, for example, toilet paper, kitchen paper towels, napkins, paper tissues, cosmetic wipes, paper towels, cleaning wipes and cloths.
Another subject matter of the present invention is a device to carry out the above-mentioned treatment process for old paper, comprising essentially a dissolving aggregate, optionally a vat or a dump chest, other commonly employed sorting stages in the form of a pre-sorting unit, a flotation unit, a fine-sorting unit, a washing unit as well as a deckering device, followed by a pressure dispersion device (hot-treatment stage), temperature-control device and further processing devices such as, for example, holding basins or towers and drying units to form the recycled pulp or recycled fibrous material in flat or bale form.
Moreover, there can also be machines for additional material cleaning and bleaching in the old-paper treatment installation. The order in which these machines are set up and operated can vary, depending on the required material and quality properties.
Another subject matter of the present invention is a tissue paper product in the form of base tissue paper or as a ready-to-use tissue product that is suitable for consumption, with a total germ count of less than 1000 CFU/g and a surface germ count of less than 20 CFU/dm2, which can be obtained by means of the processes described above.
This is done in a generally known manner in that the recycled pulps are fed, for example, either directly to an installation for base tissue paper production or else are dewatered, stored temporarily in flat or bale form, for example, by drying to a 10% residual moisture content and subsequently conveyed to a base tissue paper production installation consisting of a so-called constant section and the actual base tissue production machine, for example, a conventional xe2x80x9cYankee machinexe2x80x9d or a TAD (Through Air Drying) tissue machine.
In a hygiene paper processing unit located downstream from the base tissue production, a tissue product that is suited for the above-mentioned final use is then manufactured in that one or more single-layer or multi-layer feed roll(s) of the base tissue paper is/are processed on either automatic folding or roller machines to make the tissue final product. It goes without saying that no auxiliaries that would increase the germ counts in the finished tissue product are used within the scope of the further processing. Special attention should be paid to this when glue, lotions or other components are used that could conceivably be susceptible to microbial contamination.
Biocide as defined in the present invention refers to commonly employed environmental chemicals, especially environmental chemicals used in the paper industry, that are utilized to control harmful, minute organisms, especially microorganisms. The primary effect of many biocides is selective for individual groups of microorganisms, but often such biocides such as, for example, DDTxe2x80x94which belongs to the organic chlorine compoundsxe2x80x94can also accumulate via the food chain in other species that do not belong to the actual target groups, thus posing a chronic or acute risk to other groups of a community of living creatures. Biocides typically used in the paper industry are, for example, sodium chloride, sodium peroxide, sodium hydrogen sulfite, 1,4-bis-(bromoacetoxy)butene, tetramethylthiuram disulfide, 3,5-dimethyl-tetrahydro-1,3,5-thiadiazine-2-thione, bromo-hydroxyacetophenone, disodium cyanodithioimido carbonate, potassium-N-methyldithio carbamate, N-(2-p-chlorobenzoylethyl)-hexaminium chloride, methylene bis-thiocyanate, potassium-N-hydroxymethyl-Nxe2x80x2-methyl dithiocarbamate, sodium-2-mercaptobenzo-thiazole, sodium hexafluorosilicate, 2-oxo-2-(4-hydroxy-phenyl)-acetohydroxim acid chloride, N-[xcex1-(1-nitroethyl)benzyl]-ethylene diamine, 2-bromo-2-nitropropanediol-(1,3), aqueous solution of p-hydroxybenzoic acid ester (methyl-, ethyl- and n-propylester of p-hydroxybenzoic acid as well as its sodium salts) in hydrogen peroxide (35% by weight), mixtures of 5-chloro-2-methyl-4-isothiazolinon-3-one and 2-methyl-4-isothiazoline, mixtures of tris-(hydroxymethyl)-nitromethane from 5-chloro-2-methyl-4-isothiazolinon-3-one and 2-methyl-4-isothiazoline, a mixture of N,Nxe2x80x2-dihydroxymethylene urea and 1,6-dihydroxy-2,5-dioxahexane and 5-chloro-2-methyl-4-isothiazolinon-3-one and 2-methyl-4-isothiazo-linon-3-one, 2,2-dibromo-3-nitrilopropionamide, a mixture of phenyl-(2-chloro-2-cyanovinyl)-sulfone and phenyl-(1,2-dichloro-2-cyanovinyl)-sulfone and 2-phenyl-sulfonylpropionitrile, 1,2-benzisothiazoline-3-one and mixtures of the preceding products, sorbic acid, p-hydroxybenzoic acid ethyl- and/or -propylester, formic acid, benzoic acid, adduct from 70% benzyl alcohol and 30% formaldehyde.
The term chlorine compounds refers to inorganic as well as organic chemicals that either contain chlorine or else split off chlorine and that are commonly employed especially in the paper industry. These are, for instance, alkali hypochloride, earth alkali hypochloride, chlorine and chlorine dioxide.